U.S. patent number 10,620,099 [Application Number 15/524,911] was granted by the patent office on 2020-04-14 for solid projectile without stabilizing structure for bird strike tests consisting of a gel comprising glycerol.
This patent grant is currently assigned to ETAT FRAN AIS represente par LE DELEGUE GENERAL POUR L'ARMEMENT. The grantee listed for this patent is ETAT FRANCAIS REPRESENTE PAR LE DELEGUE GENERAL POUR L'ARMEMENT. Invention is credited to Christian Bressan, David Denaux, Gerard Diulius, Henri Etcheto, Christian Jean Marie, Patrick Sarrazac, Georges Vidal.
United States Patent |
10,620,099 |
Bressan , et al. |
April 14, 2020 |
Solid projectile without stabilizing structure for bird strike
tests consisting of a gel comprising glycerol
Abstract
Disclosed are a projectile and a method of its manufacture for
the field of investigating the strength properties of a solid
material by application of a mechanical force and more particularly
for bird strike tests consisting of a gel including glycerol. A
projectile 1 according to the invention may have a central portion
4 of cylindrical shape including a substantially hemispherical
portion 2, 3 at each of the ends thereof.
Inventors: |
Bressan; Christian (Balma,
FR), Etcheto; Henri (Toulouse, FR), Denaux;
David (Labege, FR), Vidal; Georges (Plaisance du
Touch, FR), Diulius; Gerard (Saint-Jean,
FR), Sarrazac; Patrick (Toulouse, FR), Jean
Marie; Christian (Labastidette, FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
ETAT FRANCAIS REPRESENTE PAR LE DELEGUE GENERAL POUR
L'ARMEMENT |
Paris |
N/A |
FR |
|
|
Assignee: |
ETAT FRAN AIS represente par LE
DELEGUE GENERAL POUR L'ARMEMENT (Paris, FR)
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Family
ID: |
53039455 |
Appl.
No.: |
15/524,911 |
Filed: |
November 6, 2015 |
PCT
Filed: |
November 06, 2015 |
PCT No.: |
PCT/FR2015/000204 |
371(c)(1),(2),(4) Date: |
May 05, 2017 |
PCT
Pub. No.: |
WO2016/071587 |
PCT
Pub. Date: |
May 12, 2016 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
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US 20170350799 A1 |
Dec 7, 2017 |
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Foreign Application Priority Data
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Nov 6, 2014 [FR] |
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14 02511 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N
3/30 (20130101); F42B 12/745 (20130101); G01M
7/08 (20130101); F42B 12/36 (20130101); F42B
12/34 (20130101); F42B 8/14 (20130101); F42B
5/025 (20130101); B64F 5/60 (20170101); G01N
3/62 (20130101) |
Current International
Class: |
G01N
3/30 (20060101); F42B 5/02 (20060101); F42B
12/36 (20060101); F42B 8/14 (20060101); F42B
12/74 (20060101); F42B 12/34 (20060101); G01M
7/08 (20060101); B64F 5/60 (20170101); G01N
3/62 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 172 734 |
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Apr 2010 |
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EP |
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2013/109634 |
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Jul 2013 |
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WO |
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Other References
International Search Report, dated Jan. 28, 2016, from
corresponding PCT application. cited by applicant .
FR Search Report, dated Oct. 14, 2015, from corresponding FR
application. cited by applicant.
|
Primary Examiner: Huls; Natalie
Assistant Examiner: Jenkins; Jermaine L
Attorney, Agent or Firm: Young & Thompson
Claims
The invention claimed is:
1. A solid projectile without stabilizing structure for bird strike
tests, the projectile comprising between 30% and 40% of
glycerol.
2. The projectile according to claim 1, wherein the projectile
comprises a gelling agent, glycerol, microbeads and water.
3. The projectile according to claim 2, wherein the microbeads have
a size lower than 200 .mu.m.
4. The projectile according to claim 2, wherein the microbeads are
made of phenolic resin.
5. The projectile according to claim 2, wherein the gelling agent
is selected from the group consisting of: gelatin, agar,
carrageenan, pectin, konnyaku, carob gum, alginates, gellan gum,
hypromellose, hydroxypropylmethyl cellulose, xantham gum and
starch.
6. The projectile according to claim 1, wherein the projectile has
a hemispherical shape on either side of a cylindrical central
portion.
7. The projectile according to claim 6, wherein the central portion
has a diameter between 90 mm and 130 mm for a height between 60 mm
and 100 mm.
8. The projectile according to claim 7, wherein the central portion
has a height of 70.1 mm and a diameter of 95 mm.
9. The projectile according to claim 7, wherein the central portion
has a height of 88.3 mm and a diameter of 119.7 mm.
10. The projectile according to claim 1, wherein the projectile has
a density between 950 kg/m.sup.3 and 970 kg/m.sup.3.
11. A solid projectile without stabilizing structure for bird
strike tests, the projectile comprising: 2% to 8% of the gelling
agent, 30% to 40% of glycerol, 1% to 5% of microbeads, and at least
47% of water.
12. The projectile according to claim 11, wherein the projectile
comprises 5% of the gelling agent.
13. The projectile according to claim 11, wherein the projectile
comprises 35% of glycerol.
14. The projectile according to claim 11, wherein the projectile
comprises 3.2% of microbeads.
15. The projectile according to claim 11, wherein the projectile
comprises 56.8% of water.
16. A method for manufacturing a solid projectile without
stabilizing structure for bird strike tests, where the projectile
comprises more than 20% of glycerol, the method comprising: mixing
a gelling agent in the glycerol for providing a binding; mixing
microbeads with the binding; adding hot water to the microbeads and
binding under stirring for several minutes to produce a resulting
mixture, the hot water having been previously heated at a
temperature between 80.degree. C. and 85.degree. C.; and pouring
the resulting mixture into a mold having a shape of the
projectile.
17. The method according to claim 16, wherein the step of pouring
the resulting mixture into a mold is performed when the temperature
of the mixture is between 50.degree. C. and 54.degree. C.
18. The method according to claim 16, where the projectile
comprises between 30% and 40% of glycerol.
Description
The invention relates to the field of investigating the strength
properties of a solid material by application of a mechanical force
and more particularly relates to a projectile, comprising a
material similar to a gel and able, thanks to its shape and its
physical properties, to simulate a bird.
BACKGROUND OF THE INVENTION
In the aeronautics field, an important normative system exists due
to the criticality of a potential accident. Each aircraft is forced
to meet a set of rules in order to be certified and thus allowed to
fly and convey passengers. This regulation can change according to
the problems encountered in flight and also the materials used and
the manufacturing methods. The justification methods have also
changed even if a major part is still performed by tests. The
changes have always been performed in order not to deteriorate the
passenger safety level.
The certification of an aircraft indicates that the latter meets
the navigability regulatory requirements. Its structure must
withstand the exceptional loads (static strength) that are
encountered, but also the application of repeated loads
(endurance). For the requirements, the demonstration of a safe
behavior up to the limits of the specified field is required. Other
parts of the regulation include requirements related to the bird
strike resistance. Thus, the manufacturers have to demonstrate to
the certification authorities that each sensitive component of an
apparatus, such as the cockpit, the foredeck and the wing leading
edge, which may be struck by a bird, withstands such strike or at
least such strike does not affect in a catastrophic manner the
flight safety and the landing of the aircraft. The authorities also
require that the final test be performed with an actual bird. For
the sake of reproducibility and uniformity, and for avoiding the
use of live or dead birds, artificial birds, also called substitute
impactors, have been developed and are used as a substitute for
actual birds. The idea of a substitute impactor has been studied
since about twenty years but, although the manufacturers are now
used to employ it during the phases of designing the parts, none of
them have manifested the will to use it for the certification
tests. The emergence of dynamic calculation over the past years
should give a second life to the substitute impactor, which can be
modeled far more easily, and encourage the manufacturers to use it
for the development and certification tests, to the extent that it
could be validated by the entitled authorities of European and
American civil aviation (particularly EASA and FAA).
Some of these impactors are constituted by a mixture of water and
gelatin and are in particular used for simulating the suction of
birds by a reactor. However, this gelatin-based mixture has to be
thick enough to allow to be handled and projected on the target
such as a reactor or an aircraft wing. This can be provided by
mixing a significant amount of gelatin with hot water, and then
letting the mixture stand such that the resulting gel is
sufficiently rigid, solid and stable for allowing it to be fired at
a speed representative of specific conditions of actual strikes of
birds on flying aircrafts.
However, a disadvantage is that the gel tends to have a rubbery
consistence, which does not entirely reproduce the actual behavior
of a bird. The high level of elasticity can cause the rebound or an
unusual crushing of the impactor upon striking while an actual bird
would not do it.
Furthermore, the projectiles are fired into the areas of the
elements to be tested at a high speed, for example using a gas gun,
such as using compressed air. Due to the high speeds and the high
air resistance resulting therefrom during the projectile flight
phase, the impactor is deformed, which affects the quality of the
simulation of an actual bird and the quality of the tests, if only
due to the changes made to the trajectory and/or to the speed of
the projectile, in particular regarding the measurement of the
latter that needs to be acquired.
To prevent these disadvantages, U.S. Pat. No. 8,220,396 describes a
projectile comprising a stabilizing structure, for example made of
cardboard and with a honeycomb shape, surrounded by gel formed, for
example, from water and gelatin or a compound similar to a jelly,
such as rubber, silicone, soap glycerin, starch, polymer gel,
rubber, latex and/or modelling paste.
This stabilizing structure, on one hand, has a high rigidity for
preventing the projectile from deforming during flight and, on the
other hand, is very fragile such that it is almost immediately
destroyed upon striking the target and thus, according to the
author, has almost no influence on the behavior of the projectile
upon striking.
Patent application US2010/0077832 describes a projectile comprising
a solid foam and a gel. The foam phase is generally a polymer foam
such as for example phenolic resin foam, polyurethane foam,
polyester sponge foam or urea-formaldehyde resin foam.
This foam can have an open structure to allow the gel, when it
separates, to be suctioned, by capillarity, into the pores of the
foam, the porosity of the latter being preferably higher than 80%.
It is indicated that this foam can simulate the skeleton of a
bird.
The gel is preferably an aqueous gel. The gelling agent can be
selected from the following list: gelatin, agar, carrageenan,
pectin, konnyaku, carob gum, alginates, gellan gum, hypromellose,
hydroxypropylmethyl cellulose, xantham gum and starch. Preferably,
the gelling agent is gelatin. It can be absorbed entirely or not
within the foam.
The projectiles according to these patents have a good capacity to
retain their sizes in flight, but add additional elements which
make the projectile manufacture more complex and, regardless of the
authors, add elements which affect the quality of the tests and
especially their similarity to a live bird.
SUMMARY OF THE INVENTION
The aim of the invention is to solve the above-mentioned
disadvantages by providing a projectile able to perfectly simulate
the strike of a live or dead bird on a structure, easy to
manufacture, and having almost no deformation in flight.
The solution provided is a solid projectile without stabilizing
structure for bird strike tests consisting of a gel comprising
glycerol.
The use of glycerol allows to improve the preservation of the
projectile but above all significantly increases the dimensional
stability of the projectile in case of high speed flight, typically
higher than 150 m/sec.
According to a particular feature, a projectile according to the
invention comprises more than 20% of glycerol, and preferably
between 30% and 40% of glycerol.
According to a feature, a projectile according to the invention
comprises a gelling agent, for example agar, glycerol, microbeads
and water. The microbeads preferably have a size lower than 200
.mu.m and can, for example, be made of phenolic resin.
The presence of microbeads enhances the breaking of the projectile
upon striking and improves the quality of the simulation of the
behavior of an actual bird.
In order to further increase the quality of the simulation of the
behavior of an actual bird, a projectile according to the invention
comprises: 2% to 8% of a gelling agent, and preferably 5%, 30% to
40% of glycerol, and preferably 35%, 1% to 5% of microbeads, and
preferably 3.2%, at least 47% of water, and preferably 56.8%.
According to another feature, the gelling agent is selected from
the following list: gelatin, agar, carrageenan, pectin, konnyaku,
carob gum, alginates, gellan gum, hypromellose, hydroxypropylmethyl
cellulose, xantham gum and starch.
Such an artificial projectile is highly homogeneous, thereby
facilitating its modelling and allowing to create any shape, and it
has a behavior that is more reproducible than that of live or dead
birds and as close as possible to their average behavior, while
being conservative.
According to another feature, a projectile according to the
invention has a hemispherical shape on either side of a cylindrical
central portion.
According to an additional feature, the central portion has a
diameter between 90 mm and 130 mm for a height between 60 mm and 00
mm and, preferably, a central portion with a height of 70.1 mm and
a diameter of 95 mm or a central portion with a height of 88.3 mm
and a diameter of 119.7 mm.
According to another feature, the projectile has a density between
950 kg/ms and 970 kg/ms.
According to a particular feature, a projectile according to the
invention comprises a central portion with a height of 70.1 mm and
a diameter of 95 mm for a mass of about 908 grams.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages and features will become more apparent upon
reading the description of several embodiments of the invention,
together with the appended drawings in which:
FIG. 1 shows an example for the shape of a solid projectile without
stabilizing structure according to the invention,
FIG. 2 shows the type of pressures measured on a plate as a
function of time, the curve No. 1 being for the chicken and the
curve No. 2 being for the impactor (AM) according to the
invention,
FIG. 3 shows an example of view, under a microscope, of the
microbeads within a projectile according to the invention,
FIG. 2 shows a table regrouping calculations of: the average of the
correlation coefficients obtained on the various sensors, the
average of the amplitude ratios obtained on the various sensors,
the ratio of the kinetic energies of the chicken and the impactor
(AM),
wherein the calculations have been performed from measurements of
pressure and of deformation of said plate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an example for the shape of a solid projectile 1
without stabilizing structure according to the invention. It has a
central portion 4 of cylindrical shape comprising a substantially
hemispherical portion 2, 3 at each of its ends. The height of the
central portion 4 is about 70.1 mm and its diameter is equal to
about 95 mm, thereby having a maximum length of about 165.1 mm for
a mass of about 908 g.
This projectile is composed of: 5% of gelling agent, namely agar
with high solubility, 35% of glycerol, 3.2% of microbeads, 56.8% of
water.
The preparation thereof was as follows 1:
1. Heating water at a temperature between 80.degree. C. and
85.degree. C.,
2. Mixing the gelling agent, namely agar, in the glycerol for
obtaining a binding,
3. Mixing the microbeads with the binding,
4. Adding hot water smoothly and under stirring for several
minutes, for example 5 minutes,
5. Cooling the resulting mixture to a temperature between
50.degree. C. and 54.degree. C., and then pouring the resulting
mixture into a mold having the shape of the projectile,
6. Cooling at ambient temperature.
After complete cooling, the resulting projectile is unmolded and
then stored, for example under plastic film, at a temperature
preferably between 5.degree. C. and 10.degree. C.
Tests for comparison between the consequences of a chicken strike
and that of an impactor (AM) according to the invention have been
performed with a test piece constituted by a Kevlar plate on the
rear face of which have been arranged pressure sensors FX, FY, FZ
and strain gauges.
As shown in Table 1, first tests 2 and 17 were intended to describe
the consequences of a strike of a chicken of 925 g and of an
impactor according to the invention of 900 g which were thrown
against the front face of said plate with an angle of 45.degree. at
a speed of 117 m/sec, respectively 123 m/sec, and second tests 2bis
and 17bis were intended to describe the consequences of a strike of
a chicken of 905 g and of an impactor according to the invention of
900 g which were thrown against the front face of said plate with
an angle of 45.degree. at a speed of 165 m/sec, respectively 167
m/sec.
TABLE-US-00001 TABLE 1 Plate Firing Speed Mass Energy Target Angle
Projectile No. No. (m/sec) (g) (J) Kevlar 45 Substitute 678 2 123
900 6808 Chicken 679 17 117 925 6331 Substitute 678 2 bis 167 900
12550 Chicken 679 17 bis 165 905 12319
The pressures applied on said plate, measured as a function of
time, are the same type as those shown in FIG. 2, the curve No. 1
being for the chicken and the curve No. 2 being for the impactor
(AM) according to the invention. It can be noted that an offset of
the pressure peaks increases over time.
Also, the comparison between the general shape of both curves is
performed by calculating, as a function of time, the correlation
coefficient of both curves between the initial time and time t.
This coefficient is between -1 and 1; it is equal to 1 when these
curves vary exactly in phase, and is equal to -1 if they are in
antiphase. Furthermore, for quantifying the similarity of the
importance of the deformations applied, it is necessary to
calculate the amplitude ratio, namely the ratio of the efficient
values of the signals.
From these results, have been calculated: the average of the
correlation coefficients obtained on the various sensors, the
average of the amplitude ratios obtained on the various sensors,
the ratio of the kinetic energies of the chicken and of the
impactor (AM)
Table 2 provides the results of the calculations mentioned
above.
TABLE-US-00002 TABLE 2 Test parameters Energy Average of amplitude
Speed Average of correlations Chicken/AM ratios Chicken AM Angle
(m/sec) FX FY FZ Gauges deviation FX FY FZ Gauges 17 2 45.degree.
120 91% 89% 96% 96% 92% 84% 87% 89% 96% 17 bis 2 bis 45.degree. 166
91% 94% 99% 95% 98% 63% 84% 100% 98%
The values of 95% for the averages of the correlations are very
high, thereby indicating that the time profile of the signals
related to the chicken and those related to the impactor are close
while the amplitude ratio is of the same order as the ratio of the
incident energies, which means that, with identical energy, the
impactor applies deformations equivalent to those of a chicken.
FIG. 3 shows an example of view, under a microscope, of the
microbeads within a projectile according to the invention. In this
example of embodiment, the microbeads are made of phenolic resin
and have a diameter lower than 200 .mu.m. On this picture, the size
of the present microbeads is between 10 .mu.m and 130 .mu.m.
* * * * *